This invention relates generally to control circuitry, and more particularly to a circuit for adjusting the power in a solenoid in response to line voltage changes.
In the operation of the solenoids, such as are often used in electronically operated motor controllers, it is not infrequently desirable to adjust the power input to the solenoid in response to abnormal operating conditions, or even at times in normal transient operations. For example, if the line voltage supplying power to the solenoid drops significantly below its normal value, and it is required that the solenoid generate enough force to keep the con tactor engaged, it is desirable to increase the power to the solenoid to prevent or overcome drop-out of such solenoid. Additionally, during normal closing operations, it may be desirable to increase power to the solenoid because such larger than normal current will result in a more positive pull-in of such solenoid. During operation, in shock or vibration situations, a heavier than normal current will lessen the probability of a drop-out.